The invention is generally related to sensors and, more particularly, to systems for detecting hydrocarbon emissions and for tracking the history of equipment tested for emissions.
The desirability of reducing harmful hydrocarbon emissions has long been recognized. Accurate and reliable emissions monitoring has a high priority in many geographical areas and progressively more stringent emission control standards have been promulgated, particularly in high air pollution areas. For example, Rule 1173 of the State of California relates to the Fugitive Emissions of Volatile Organic Compounds and has monitoring, record keeping and reporting requirements. The rule is meant to apply to petrochemical facilities, including refineries, pumping stations and storage facilities. Hydrocarbon emissions are to be monitored, identified and recorded and if the emissions exceed certain limits, repair action is to be undertaken.
Federal Rule 49 (37 CFR .sctn.191 and .sctn.192) is another emission standard which addresses somewhat different emissions but nevertheless imposes monitoring, recording and reporting requirements on petrochemical facilities.
In general, these rules require that each possible point of escape for hydrocarbons, or "release point", in a petrochemical facility be identified, monitored and tracked. That is, each fitting, joint, packing gland, flange and other possible points where hydrocarbons could escape must be monitored and tracked. Leak limits have been established and in the event that emissions from a release point exceed the limit, corrective action must be taken. Under California Rule 1173, the type of corrective action depends upon the severity of the leak. For example, a slight leak, but one that exceeds the threshold nevertheless, may be subject to repair within fourteen days of detection while a massive liquid leak may be subject to immediate repair.
Tracking the leak history of a release point is important because the favorable leak history of a release point may, under California Rule 1173, qualify that release point for a reduced monitoring schedule. Conversely, a poor leak history may result in a requirement that the part be replaced or that the joint be reformed or that other corrective maintenance action be taken.
One prior technique for monitoring such emissions involved manual sensing and recording. Emissions were sensed by a portable vapor analyzer, the results were displayed by that analyzer and the operator would then record the results manually. Such a system had a potential for operator error, including mis-identification of the release point, incorrectly recording the release point identification, misreading the sensor, incorrectly recording the sensed emissions, illegibility of writing, and other possible errors.
One desired effect of the above-mentioned emission standards is to cause increased automation of monitoring and tracking efforts. Methodologies involving automation of as many steps as possible are preferable. It is believed that such automation will result in more consistent and reliable monitoring of emissions and record-keeping. Optimally, the equipment used for identifying, monitoring, recording and reporting would define a closed system in which human error would be minimized. Direct communication between all system components involved in identification of the release point under test, sensing emissions from that release point, data recording and processing, and report generation would provide an integration of the system to an extent that the system would be more reliable and operator error would be minimized. The invention fulfills these needs.